Liquid-tank-level gauge



May 13, 1930.

Jj FENTRESS Filed July 25, 1925 i:Ill Hl LIQUID TANK LEVEL GAUGE num: mm1 m 2 Sheets-Sheet May 13, 1930. A J, FENTRESS 1,758,077

LIQUID TANK LEVEL GAUGE Filed July 25, 1925 2 sheets-sheet 2 l applicable to the use 'of determining the sible in devices of this class.

heated May 1 3, 193e UNITED f STATES APixrlezN'ry OFFICE JAMES FENTBESS, OF CHICAGO, IIIIIIIJIN'OISA LIeum-raNx-EEVEL GAUGE Application vmea my 25, 1925,. serali no. 46,014.

This 4invention relates -to devices operating on the hydrostatic principle to indicate a level of liquidin a tank, and is especially amount of gasoline and other liquids in tanks or other containers on an automobile travel-5' ing over more or less irregular surfaced roads. A, The objectl ofthe invention is to provide a device of this kind in which changes in depth of gasoline or other liquid in a tank are much more accurately indicated on the suitably located gauge, usually on the dash of the automobile, than has heretofore been pos- 'The inventioncoilsists in means for attaining the foregoing and other objects; which can be easily and cheaply made; which is satisfactory in use and is mot readily liable to get out of order.

, More particularly, the invention consists in numerous features and details of construction hereafter more fully set forth in the illustrating the application of this invention to the gasoline tank of anl automobile.

Figure 2 is a similar view, showing. a modified constructionof the device of Figure 1 inv which the condition of a particular quantity of gasoline in the'tank, specifically the bottom gallonin the tank, is magnified and especially clearly shown in the indicator or gauge, visible to the operator of the automobile.

' Figure 3 :is a. modified form .of the structures of Figures 1 and 2, showing means for accurately registering at the gauge on a scale of uniform dlvisions, the-quantity of gasoline in a tank of non-rectangular cross-section.

Figure '4 isa detailed, sectional view 4'5 through a pump, especially designed for usev in connection with the mechanism of this invention.-

- Figure 5 is a side viewA of. an automobile "dash and steering post, showing the application of the mechanism of this inventigin therel. i l

Figure 6`is a face view from the right of Figure 5, `the steering wheel being removed.

Figure 7 is a vertical, sectional, detailed view through the gauge mechanism appearin inFigure 6. igure 1 of the drawings shows a liquid, specifically a gasoline, tank 10, of rectangular form, having entering it and extending to a point 12 .near its bottom, a comparatively small delivery pipe v14. The upper end of this pipe 14 has above the'tank'a laterally'eiztcnding'end 16, entering a valve enclosing coupling 18. Entering the other` side of thisv i coupling 18, beyond the more or less conventional checkvalve 20 therein Jis a downwardly extending pipe or arm 22 of the U-tube 24, whose opposite, upwardly extendingv arm 26 enters through a coupling 28 the substantially larger reading, glass tube 30, located within sight of the -user of vthe device.,usually on the dash ofethe automobile. The upper end of this reading glass tube 30 terminates in a comparatively small discharge port 32 controlled by an immediately adjacent, more or less conventionalcheck-valve 34. The checkl valve 34 is so designed and located that, while it is normally open, it will, if there is abnormal pressure in tank 10, be closed by the liquid rising and lifting thevalve against the port,

and thus prevent the indicating liquid 36 bei ing blown out through port 32 when and if an abnormal pressure is created in the tank 10. Similarly, the check-valve 20 is so designed and located as to normally afford-a free pas-l sage4 between tubes 16 and 22, but to close -Whenever an abnormal suction is created in tank 10 which would, but for this valve, draw the indicating liquid 36 out of the tube 24 into the tank. The abnormal pressure and abnormal suction in tank '10 are always possible because tank 10 is connected by devices not shown in the drawing, more or. less directly to the automobile engine which takes the gasoline or other liquid 38 out of the tank forconsumption by the engine pr other mechanism. y

It is -well understood in this artthat if accurate results are to be obtained in a device of this character, the tube'14 must be keptfilled with air and clear ofliquid vdown to the lower tube 24.

In detail, the pump 40 of Figure 4 is provided with a conventional form of checkvalve 50, normally seated by a spring 52 to prevent the escape of air or liquid from pipe 22. In the pump cylinder and opposite this check-valve is the hollow piston 48, provided with an end port 54 and a side port 56. The piston 48 is rotatable within the cylinder and the device is so constructed that the operator can bring side port 56 of the piston into register with side port 58 in the cylinder to thereby admit air through ports 58 and 56, to the interior of the piston and thence through port 54 into the cylinder. In operation of the pump when the cylinder 48 is drawn back beyond port 58 the air is admitted and the forward stroke compresses it until piston 48 strikes valve stem and opensvalve 50, whereupon air passes into line 22. The Spring 60 forces piston 48 back far enough to relieve its pressure on valve stem 55 so valve 50 will certainly close. On handle 44 is a 'mark indicating the position that allows the gauge tobe* vented. In this'position when piston 48 is pressed against valvev stem 55, valve 50 is open and the vents 56-58 coincide so that air under pressure in line 22 passes valve 50 through port 54--56-58 thus venting line 22 and causing U gauge to drop to zero indicating an empty tank. The pump handle 44 turned in any position except the special one above indicated acts as a pump and vents 56--58 do not coincide and the pump is again capable of forcing air (ompletely out of tube 14 in tank. This ventii g of the U gauge is important and is a method of proving that the U gauge is in order and operating correctly. Tithout a venting device, it would not be known whether the gauge liquid had been changed in some Way by evaporation, etc.

Automobile dash boards on which the gauge is usually applied are usually from four to six inches in height and prior constructions, this has meant that the entire length of the U-tube which does the measuring is limited to these dimensions. `When such a small U-tube of the prior art was used, it was found necessary to placein the gauge a liquid about three times as heavy as gasoline in order to get a movement on the U-gauge of one-third the depth of the gasoline tank. These tanks being about ten inches deep, there is a movement in the U-tube of one-third rof ten inches or about three inches. The liquid commonly employed for this purpose formerly was bromoform which is costly, evaporates easily and cannot be easily procured. To do away with the requirement for the use of bromoform or other equally expensive liquid, the structure of Figure 1 provides the relatively short reading glass tube 30 of comparatively large diameter on the automobile dash, equipped with graduations 62 to be read by the observer, said tube 30 being in direct communication with the much longer U-device 24, having the pipes 26 and 22 of very much smaller diameter than the diameter of pipe 30.

-Iu actual automobile practice, installation of this structure requires that a U-tube 24 extend substantially below the dash board 64 of the automobile. One way of taking care of this is illustrated in Figure 5 in which the U-tube 24 extends along and is strapped by baud 66 to the stationary steering post 68 of the automobile.

The results obtained by this construction are worth while first, kerosene or other light, non-evaporating, non-freezing oil, which is cheap and readily procurable everywhere, may be used in the U-tube mechanism; second, by properly proportioning the diameters of the tube 30 to the pipes 26 and 22 of the U- mechanism 24, the extensive movement of the kerosene or the like in the'U-tube becomes the required three inches or the like movement in reading glass tube 30. By initially varying the diameters of the pipes 30 and 22, vthe range of movement in the liquid in pipe 30 and consequent length of the scale 62 may be varied to suit the willof the initial constructor.

The structure of Figure 2 differs from that of Figure 1 in the substitution of a large safety chamber 70 for the safety valve mechanism 20, this chamber functioning to receive and retain all the indicating liquid 36 should there be undue suction in tank 10, it being impossible because of the size of this chamber for the suction in comparatively small pipe 14 to draw any of the liquid 36 above and beyond this chamber 70. The structure of Figure 2 further differs from that of Figure 1 in the construction of an enlargementl or curve 72 in pipe 22, at the point occupied by the upper end 74 of liquid 36 at the time there is less than one unit of liquid to be measured in the tank 10,-that is to say, curve 72 is so placed that it will become operative when gasoline or the like between the points 76 and 78 of the tank of Figure 2 is to be measured. The use and positioning of coil 72 arises from the fact that that the most interesting content of a tank is the last gallon, i. e., the bottom gallon in the tank, because it is this gallon which tells how far the automobile user can go before he has to refill his tank. Inserting the coil 72 in pipe 22n is the samething as increasing the size of the pipe atthat point to, say, the diameter of reading y initial construction of the device be increased or diminished within limits to any extent desired,

' In Figure 3, a non-rectangular-in'the particular lcase .shown, a cylindrical-gasoline tank 1()a is provided and the mechanism of Figures 1 and 2 is modified to make a uniform scale on indicating glass tube b by substituting for pipe l22 a pipe 22b so sha \ed in internal capacity that the scale 82 a jacent to glass 30D will-read inuniform divisions. The

" principle lis exactly the vsame as the. installation of the curve 72 inI pipe 22B. By varying the sha e 'of pipe 22", the divisions of scale f 82 may ethrown off from uniformity as the -initial constructor may desire. In the cony'struction of this figure, equlizingl air tank 40 tion register accurately in spite of the unlevel but whenthe auto tank is full, the gauge 84 is inserted between pump 40 and the right hand arm of the U-tube 24, this tank 84 acting like the ordinary equalizing dome on more or less antiquated fire engines. to equalize in the water pressure irregularities in the engine piston movements; In other words, this tank 84 insures a substantially uniform flow of air into the U-tube mechanism as pump 40 is manipulated, instead of a pulsating flowas is the case inthe construction of Figure 1.

In order that the mechanism of this invenroads, the two arms of the U pipe 24, as shown in Figures 6-7, are brought as close together as is practical at the' dash` This avoids variation in the two heads of theU liquid-forthelv last gallon in the auto tank,

liquid heads are separated from eachother out ofthe p rpendicular'dropped fromglass 30 by the distance between that perpendicular andthe eXtreme position 24E-of Figure 5.

, This diii'erence between the two lheads, of

liquid in the U will cause a readingon the glass too great, when thecar is going up hill, and too little when going down. I have coneluded to neglect this as it is temporary. The above inaccuracy occurring for up and down hill only when the position of the U is bent .a

ing on the gauge only about one tenth inch I in error which I amneglecting..

The mechanism heretofore described afords means in which an inexpensive operating liquid, such as kerosene,jca n be used with great accuracy of results on the scaleof gauge tube 30, and with the capability of being constructed so as to make the scale on the tube 30 in any proportion which the designer may think desirable for best results in the operation of the automobile or the like to which the device may be applied.' L Obviously, the mechanism may be applied to 'airsh'ips and vmany other devices besides an automobile, without departing from this invention.

, It is specifically pointed out that the aii` introduced by the pump 40 .must be introduced in very small quantities in lorder not to disturb the reading of the gauge. It isfor this reason that the compensating pressure tank of Figure 3 and the other. special constbrluctions of the drawings are highly desira e.

Oneadvantage of making the reading glass tube larger than the main U-tnbe is to render the expansionl of the liquid in the UA-tube,

sol

due to heat,'a negligible quantity as vit api' pears in the larger reading glass.

It is desirable to make the tube 22n of soft metal so that the shape and character of the bend 72 may be varied to thereby adjust the position of the liquid in theU-tube to any predetermined zero point on the reading glass.

Having thus described my invention, what I claim as new and desire td secure by Letters Patent is: Y

1. In combination with a tank for containing a liquid, a U-tube, a tubeconnecting said f U-t'ube with said tank at the minimum depth within the latter at which the level of liquids Y therein is to be measured, an indicatingele` mentin' said U-tube 'being movableby variations in the level ofthe liquid in' said tank,

an indicator associated with said .U-tube, adapted to register kthe movements of said indicating element, and means included solely within said U-tube and spaced from said indicator, whereby the movement of said indicating element proportionate to they variations of the level of the liquid in the tank is increased as the `liquid 'becomes exhausted fromthetank. 2. In combination'witli a tank for containing a liquid, an indicator glass of uniform" diameter throughout, an indicating liquid vinsaidl glass, a U-tube', one -en'd' thereof being connected to said indicator glass, means conizo forward 0I' .bak '0f the CarS length! The necting the other end of said tube with said` the arms of same behind the facing of the car '1115er down hill, but only be affected by side 65 tilts-the side tilts of standard roads showmeansfor increasing thecapacity of said U- 130 disposition 0f the U across the Can/hopping 'tank at `the minimum'depth within thelattr 125 I at which the level of liquids Atherein is to be tube between two predetermined spaced points in its length located opposite said indicator glass over its capacity between any other two similarily spaced points in its length, whereby the movement of said indieating liquid proportionate to the variations of the level of the liquid in said tank is increased as the liquid becomes substantially exhausted from the tank.

3. In combination with a tank for' containing a liquid, means for indicating the level of liquid in the tank comprising a U-tube, a connection from one arm of the U-tube to said tank at the minimum depth Within the latter at which the liquid is to be indicated, an indicator section secured to the other arm of the U-tube, and an indicating liquid Within the U-tube, one of the arms of said U-tube at a point spaced from the indicator section being congurated so as to cause the relative proportional movement of said indicating liquid with respect to the movement of the level of the liquid in the tank to be increased as the tank empties.

In Witness whereof, I have hereunto subscribed my name.

JAMES FENTRESS. 

